A typical railcar includes a carbody that rides on one or more railway trucks or bogies. The carbody may be a freight container, a passenger compartment, a locomotive body, or any other type of vehicle used for transport by rail. The trucks support the carbody vertically and laterally while allowing sufficient rotational movement between the truck and carbody to allow negotiation of curved track.
The trucks are generally proximate to each end of the carbody and support the carbody for transport along the rail. Each truck generally includes a frame that connects a pair (or more) of wheel-sets. The frame generally includes a pair of side-frames that extend along the length of each side of the truck. A transverse frame, or a bolster, may connect the side-frames, to hold the side-frames generally parallel to one another.
Each wheel-set generally includes an axle, a pair of conical wheels, and a pair of bearing assemblies. The conical wheels are fixedly connected proximate each end of the axle. The bearing assemblies connect the wheel-sets to the side-frames to allow the conical wheels and axles to rotate together as the truck moves along the rail.
In conventional truck designs, the wheel-sets are fixed to the frame so that the fixed wheel-sets within each truck are generally parallel to one another and perpendicular to the side-frames at all times. Although this arrangement generally allows the wheels to be aligned to straight track, and roughly aligns the wheels to curved track, there is always an error in the alignment of the wheels to the curves. Even slight misalignment between the wheels and the rails causes a great deal of noise and wear, as well as creating substantial resistance to the rolling of the wheels. Another detriment of wheel/rail misalignment is that it creates the tendency for wheels to climb up the rails.
Many attempts have been made to reduce or prevent any slight misalignment between the wheels and the rail by steering the axles. One of the earliest of such attempts is described in U.S. Pat. No. 1,512 issued to I. N. Stanley in 1840—only a few years after the first Stephenson locomotive was introduced into North America. In many of the attempts, one or both wheel-sets are steerable so that the steerable wheel-set(s) can move laterally and/or longitudinally with respect to the frame and/or the other wheel-sets to adjust the alignment of the wheel-sets with respect to the rails.
Although various prior art designs incorporate linkages or levers of varying geometries and orientations to displace the wheel-sets with respect to the frame, most of these require mechanisms at both wheel sets and most require a significant force to be overcome to create the steering.
Therefore, there is a need for steered axle railway truck that reduces the misalignment between the wheel-sets and the track by using a mechanism at a single wheel set.
Therefore, there is also a need for steered axle railway truck that reduces the misalignment between the wheel-sets and the track by using a mechanism that requires less force than the prior art to create the steering.